The pacer, who has had a history of back trouble, has suffered a strain on his previous stress fracture.
"Subsequent scans have revealed an early stage aggravation of his old stress fracture," he added.
Coulter-Nile, who made his T20I and ODI debut for Australia in 2013, has not played any Test match yet. The injury thus may prevent the right-arm bowler from playing his first Test.
Informing further about the injury, Kountouris said, "Whilst this is a setback, the good news is that it has been picked up early so we are only considering a short break from bowling while we monitor him."
He added that Coulter-Nile will undergo further scans over the next month which will determine when he can return to bowling.